WO2016156233A1

WO2016156233A1 - Method and device for the continuous cutting of glass

Info

Publication number: WO2016156233A1
Application number: PCT/EP2016/056611
Authority: WO
Inventors: Thomas Rossmeier; Andreas Ortner; Jürgen Vogt; Andreas Habeck; Clemens Ottermann; Dirk Förtsch; Christian Breitbach; Stephan Behle
Original assignee: Schott Ag
Priority date: 2015-03-27
Filing date: 2016-03-24
Publication date: 2016-10-06
Also published as: JP6751407B2; CN107438585A; DE112016001424A5; DE102015104815A1; US20180037490A1; JP2018512366A; CN107438585B; US10407336B2

Abstract

The invention relates to a method for cutting a thin glass band (1) having a thickness of at most 400 μm along a longitudinal direction (100), wherein the thin glass band (1) is guided along the longitudinal direction (100) thereof over a levitation base (3) by means of a transport device (5), wherein a laser beam (7) is directed onto the thin glass band (100) in the region of the levitation base (3), which heats the thin glass band (1) at the impact point (70) of the laser beam (7) and past which the thin glass band (1) is moved in the longitudinal direction (100), such that the laser beam (7) draws a track (71) running in the longitudinal direction (100) of the thin glass band (1), and wherein a cooling fluid is blown by means of a cooling jet generator (14) onto the track (71) heated by the laser beam (7) such that the region heated by the laser beam (7) is cooled again and a mechanical tension is generated which causes the propagation of a stress crack (15) cutting through the glass band (1) in the longitudinal direction (100) along the track (71) of the laser beam (7), and wherein the cooling fluid contains vapour of the liquid at a saturation ratio of at least 0.5, or contains liquid drops, wherein the liquid drops form a contact angle on the surface of the thin glass band (1), which is smaller than that of water on the same surface.

Description

Method and apparatus for continuous separation of glass

description

The invention generally relates to the cutting of glass. In particular, the invention relates to the separation of

Braids of a glass ribbon. A common method to divide glass is that

Ritz breaking. In this case, a linear damage zone is introduced into the glass mechanically, typically with a scoring wheel. By applying a mechanical

Tension can then be easily broken up the glass along this damage zone. The disadvantage of this, however, is that the glass edge of a glass element obtained in this way can still have damage to the previously generated damage zone. Since just the edges are particularly critical with respect to a mechanical stress of the glass with tensile stresses, a cutting of a glass by scratching a significant reduction of the

Strength, especially lead to a bending load.

Flat glasses, in particular thin and thin glasses with thicknesses of less than 200 micrometers are nowadays often produced in the form of long strips. For production reasons,

for example, when retracting a glass ribbon from a preform or drawing from a melt, thickened ones typically form at the edge of the glass ribbon

Border areas, so-called borders. It is advantageous to separate these bands after the production of the glass ribbon, inter alia, to facilitate the winding on a roll or generally the further processing in thin glasses. As a result, problems can be avoided such as caused by the thicker edges emergence

mechanical stresses that cause a twist or

Warp of the thin glass bring with it.

From US 2013/0126576 AI an apparatus and a method for the continuous edge separation of a thin glass ribbon are known. In this device, initial damage is introduced into the glass ribbon with a scoring device. The scoring device is designed as a roller with an abrasive medium, which inserts damages transverse to the longitudinal direction of the glass ribbon. While the glass ribbon along its longitudinal direction over a curved

Levitationsunterlage is heated by a laser beam and cooled by a fluid, so that within the glass ribbon thermal stresses

be induced. As a result, the glass ribbon tears along an initial damage along its longitudinal direction.

The disadvantage here is, inter alia, that the

In some cases damage in the quality range of the glass ribbon extend to the initial damage

Damage in the cut thin glass band can remain.

WO 2011/026074 A1 describes a method for inserting a slit into a glass substrate. In this method, a laser beam is directed to damage and moved across the glass surface. In addition, a fluid jet is directed directly at the laser spot on the glass surface, so that the glass is cooled, even before the temperature generated by the laser beam through completely the thickness of the glass substrate is equilibrated. As a result, the thermal stress is limited to a part of the thickness of the

Glass substrate limited and the resulting slot

extends only partially through the thickness of the

Glass substrate.

Both in the apparatus and the method of US 2013/0126576 AI and in the method of WO

2011/025074 becomes the place where the thermal

Stresses for separating the glass are generated, determined by the impact of the fluid on the glass surface. A disadvantage of the device and the method of both cited documents is that said impingement of the fluid may differ from that location on the glass surface, on which the fluid jet is directed. The reason for this is a possible uncontrolled distribution of the fluid on the glass surface after the impact of the

Fluid jet. However, a precise control of the location of impact of the fluid is advantageous for processing thin glass bands, in particular to ensure consistent edge quality and strength.

Object of the present invention is therefore, a

Thin glass with thicknesses less than 400 pm, preferably less than 200 pm, in particular a thin glass ribbon with improved

Edge quality and strength to be processed by separation of borders of the glass ribbon. This object is solved by the subject matter of the independent claims. Advantageous developments of the invention are specified in the respective dependent claims.

The invention will be described in more detail below, also with reference to FIGS enclosed figures described. Show it:

1 is a schematic view of an apparatus for continuously separating glass,

Fig. 2 is a perspective view of a curved levitation pad 3 with over it

Thin glass ribbon,

Fig. 3 in the longitudinal direction of the thin glass ribbon considered a Levitationsunterlage with a flat surface and mounted thereon thin glass ribbon,

4 shows a liquid droplet on the surface of the thin glass ribbon,

5 an aerosol generator,

6 shows an inkjet printhead,

Fig. 7 is a schematic view of another

Embodiment of an apparatus for continuous separation of glass, Fig. 8 is a schematic view of another

Embodiment of an apparatus for continuous separation of glass,

9 is a schematic side view of another embodiment of an apparatus for continuous separation of glass, 10 an asymmetrical beam profile,

Fig. 11 preferred forms of Einwirkfeldern. Fig. 1 shows an example of a device 2 for

Separating a thin glass ribbon 1 along its

Lengthwise 100, in this case for separating

Edge regions, in particular of borders 10, 11 of a

Thin glass bands 1. The method that can be carried out with the apparatus 2 for separating a thin glass band 1 along its longitudinal direction 100, in this case for separating edge regions, in particular braids 10, 11 of a

Thin glass bands 1 is based on the fact that a thin glass ribbon 1 with a thickness of at most 400 pm along its

Longitudinal direction 100 is guided by means of a transport device 5 via a Levitationsunterlage 3, wherein in the area of Levitationsunterlage 3, a laser beam 7 on the

Thin glass ribbon 100 is directed, which heats the thin glass ribbon 1 at the point of impact 70 of the laser beam 7 and on which the thin glass ribbon 1 in the longitudinal direction 100th

is moved past, so that the laser beam 7 a in

Longitudinal direction 100 of the thin glass ribbon 1 extending track 71 draws. By means of a cooling jet generator 14, a cooling fluid is blown onto the track 71 heated by the laser beam 7, so that the area heated by the laser beam 7 is cooled again and a mechanical tension is generated which is sufficient to propagate the glass ribbon 1 in the longitudinal direction 100 along the track 71 of FIG Laser beam 7 severing stress crack 15 leads.

It is envisaged that the cooling fluid vapor a

Liquid at a saturation ratio of at least 0.5 or contains liquid droplets, wherein the liquid droplets on the surface of the thin glass ribbon 1 form a contact angle which is in particular smaller than that of water on the same surface. As a cooling fluid, for example, air with a relative humidity of at least 50 percent, an aerosol or isolated liquid droplets can be used. As shown in Fig. 5, the cooling jet generator 14 is formed as an aerosol generator 141 when an aerosol is used as the cooling fluid. As shown in FIG. 6, the chiller beam generator 14 may also be formed as an ink jet printhead 142 having a nozzle 143 which ejects discrete liquid droplets. The cooling fluid is by means of a

Cooling jet generator 14 is sprayed as a cooling jet 16 to the respective, previously heated by the laser beam 7 separation point, wherein the cooling jet 16 vapor of a liquid at a saturation ratio of at least 0.5 or

Contains liquid droplets. If the cooling fluid contains vapor of a liquid, i. a gaseous phase of a

vaporized liquid, it may in particular be an air jet with a relative humidity of at least 50 percent. If an aerosol is used, the cooling jet 16 is an aerosol jet 161, if isolated liquid droplets are used, the cooling jet is a droplet jet 162.

A cooling fluid, the vapor or liquid droplets

contains, can be provided, since a high cooling capacity can be achieved by the gaseous or liquid phase of the cooling fluid, which in turn to a high

thermal stress, that is to a high Voltage difference in the glass can lead.

As shown in FIG. 4, if necessary, they wet in the cooling fluid

contained liquid droplets the thin glass surface 103 as soon as they come into contact with this. Occasionally, the optionally contained in the cooling fluid steam the

Thin glass surface 103 when this gaseous phase condenses on contact. The contact angle 83, also called Benet tion angle, is - according to the common definition - the angle between the contact surface 81 of a located on the thin glass surface 103 liquid droplet 8 and a

Tangential surface 82 forms at the droplet surface through the three-phase point. This definition of the contact angle 83 means in particular that the contact angle 83, which can generally assume values between 0 and 180 degrees depending on the surface energies of the substances involved, the wetting of the thin glass surface by the droplet being stronger, the smaller the contact angle.

Accordingly, the wetting is weaker the greater the contact angle. The property of the liquid droplets contained in the cooling fluid to form with the surface 103 of the thin glass ribbon 1 a contact angle 83 which is smaller than that of water on the same surface thus means, in particular, that the liquid droplets strongly wet the thin glass surface 103.

Favorable to a high Benet zungsfähigkeit the

Liquid droplet on the thin glass surface 103 is a controlled distribution of the cooling fluid on the

Thin glass surface 103 after the impingement of the cooling jet 16. Among other things, by the high Benet zungsfähigkeit The location of the cooling fluid itself can therefore be precisely defined by the point of incidence of the cooling jet 16, since the droplets are affected by the high wetting Adhere to the glass surface immediately after impact. The possibility of the location of impact of the cooling fluid precisely, preferably by virtue of the cooling jet 16,

It is advantageous to be able to define this because the thermal stresses are generated at this location, through which the glass can be separated. In addition, due to the high wettability of the liquid droplets and the resulting large contact surface 81 with the thin glass surface 103, a high cooling capacity of the

Cooling fluid achieved.

As in the cooling fluid contained vapor of a liquid according to a preferred embodiment of the invention

Steam provided. If the cooling fluid is air, the saturation ratio of the

Cooling fluids, the relative humidity. The relative humidity is then at least 70 percent, more preferably at least 80 percent and still

more preferably at least 90 percent.

A cooling fluid designed as moist air may e.g.

be generated by allowing dry air out of one

Air source in water flow out and rise in it. The so moistened air can then the

Cooling jet generator 14 are supplied. The volume flow, ie the amount of cooling fluid per unit of time, which is sprayed by means of the cooling jet generator 14 on the previously heated by the laser beam 7 separation point, on the one hand should not be too low, otherwise the separation process start bad, run unsteady or can break off. On the other hand, the volume flow should not be too high, otherwise a thermal or

mechanical wave formation in the glass can be caused. The volume flow, in particular, may depend on the glass thickness of the thin glass ribbon 1. Surprisingly, it has been shown that with increasing glass thickness, a smaller amount of cooling air per unit time can be sufficient.

It has been found convenient to control the flow of the cooling jet, i. to choose the volume flow of the cooling fluid, depending on the thickness of the glass. In particular, it is favorable to choose the cooling jet flow higher with a thinner glass. So if the process changes from a thicker glass to a thinner glass, the cooling jet flow is increased, and vice versa. In particular, the flow can also be adjusted in proportion to the glass thickness. Thus, with a glass thickness of 50 pm, a flow which is about twice as high as the flux, which is particularly suitable for a glass of 100 μm, proves to be favorable. In general, very low flows are already sufficient, with the

optimal cooling jet flux at a glass thickness of 100 pm is almost zero. A certain cooling jet flow is always cheap. Completely without a cooling jet, the cutting process can become unstable or start badly and it can lead to demolition of the process, in which the crack stops propagating. On the other hand, too high a flow may cause thermally or mechanically Wave formation in the glass lead.

Without limitation to the embodiments, the cooling jet flow, i. the cooling fluid volume flow,

in particular between 0.001 l / h (liters per hour) and

1.0 1 / h. For glass thicknesses between 75pm and 400pm, e.g. for a glass thickness of 100 μm (in particular plus / minus 10 pm), a volumetric flow rate of between 0.001 l / h and 0.3 l / h, preferably 0.05 l / h (in particular plus / minus 0.01 l / h) may be particularly be cheap. For glass thicknesses between 5pm and 75pm, e.g. for a glass thickness of 50pm

(In particular, plus / minus 10pm), a flow rate between 0.06 1 / h and 1.0 1 / h, preferably from 0.4 1 / h (especially plus / minus 0.1 1 / h) may be particularly favorable.

As a liquid drop of the cooling fluid are provided according to an embodiment of the invention with surfactant

Suitable for water droplets. The surfactant sets the

Surface tension of the water down and increases the

Wetting. According to an alternative or additional

Embodiment, the liquid droplets may contain a monohydric or polyhydric alcohol. Alcohols also generally have a lower surface tension than water. The alcohol (s) may also be used in admixture with water. Especially suitable as

Part of the liquid droplets is also

Ethylene glycol. Its surface tension is not only lower than that of water, but ethylene glycol also has a higher boiling point.

Preferably, the glass surface is sprayed with a cooling fluid whose liquid droplets on the Glass surface have a contact angle of less than 40 °, more preferably less than 20 °.

In addition to a small contact angle, a high boiling point of the liquid phase continues to be favorable. Particularly suitable as a constituent of the liquid droplets in this regard is also ethylene glycol as a dihydric alcohol. Ethylene glycol can be mixed with water in any mixing ratio. The surface tension of ethylene glycol is not only lower than that of water, but

In addition, ethylene glycol also has a higher

Boiling point (197 ° C) on. If the boiling point is increased, the temperature point at which a decrease in the

Cooling done by the Leidenfrost effect, be shifted to higher temperatures.

In a development of the invention, by means of a scoring device 9 at the beginning of the thin glass band 1 before the impact of the laser beam 7, a damage,

or inserted an initial defect, which passes through the point of incidence 70 of the laser beam 7 to the

Initiate stress cracking.

After initiating the stress crack during the

Crack propagation is then preferably the

Scoring device 9 removed from the surface of the thin glass ribbon 1 and thus ends the damage. The

The corresponding device 2 therefore preferably has a device for removing the scoring device 9 from the surface of the thin glass band 1 after initiation of the stress crack during the crack propagation. Unlike provided in US 2013/0126576 AI, so is preferably only scratched initially. It has been shown that crack propagation after initiation can also be effected solely on the basis of the temperature gradient which can be achieved by heating with the laser beam 7 and subsequent cooling with the cooling fluid.

As scoring device 9 is preferably a scoring wheel 91, particularly preferably a scoring wheel with a structured scoring ^¬ or pressure surface used. Fig. 1 shows the

Thin glass ribbon after inserting the initial damage in

Shape of a crack. Accordingly, the scoring wheels 91 are raised here and no longer touch the glass surface. The voltage tripping is accordingly for

shown time solely due to a

Crack propagation, wherein the stress crack 15 propagates along the direction of movement of the thin glass ribbon 1 and typically in the region of the impact of the

Cooling fluid begins. The cutting wheel comes with the

Glass surface so briefly brought into contact and adds the glass ribbon an initial injury in the form of a tear, while the further cracking and crack propagation produced by the means of heating with the laser and the subsequent cooling by the cooling fluid

Temperature gradient occurs. In order to ensure the defined introduction of the tear, the glass ribbon is supported on the side facing away from the wheel by a roller 93 as an abutment 12. As an abutment 12 can also others

Facilities or means are used. It is also possible, for example, the scoring over the

Levitation pad 3 to order. In this case, the levitation pad 3 forms the counter bearing. The

Pressure force of the scoring wheel 91 is preferably smaller as 4 N, more preferably at less than 1.5 N.

The inventive method is particularly for the

Separating very long edge areas or borders,

Accordingly, particularly suitable for the edge cutting of long glass bands. In particular, in

Development of the invention provided that the glass ribbon 1 has a length of at least 10 meters, in particular in

Range of 10 to 1000 meters, wherein edge regions in the longitudinal direction 100 of the thin glass ribbon 1 are separated.

The levitation pad 3 is a compressed fluid by means of a pressure source, such as a pump 33,

preferably supplied air. The compressed fluid

escapes through openings on its surface facing the thin glass band 1, so that a gas cushion

between the thin glass ribbon 1 and the surface of

Levitationsunterlage 3 forms, which carries the thin glass ribbon 1 and stores. Instead of a pump 33 is

For example, a reservoir with compressed fluid conceivable. Furthermore, a reservoir and / or a throttle of the pump 33 and the Levitationsunterlage 3

be intermediate to a uniform

To provide output pressure. The thin glass ribbon 1 is thus transported floating in the vicinity of the cutting process by gas levitation, so that on the one hand the

Ambient air acts as a thermal insulator and

On the other hand, the entire Rayleighlänge of the laser focus can be exploited as a cutting area. Preferably, the volume flow of the levitation transport is adjusted according to the glass thickness and the resulting weight force via the pressure of the compressed fluid to a optimal position of the band in the working volume of the laser 72 set. For the preferred glass thickness of the

Thin glass bands 1 of less than 400 pm, preferably less than 200 pm, according to one embodiment, the pressure of the fluid supplied to the levitation pad in the range of 0.1 to 4 bar, preferably in the range of 0.1 to 2 bar, particularly preferably in the range of 0 , 2 to 1.0 bar.

The transport device 5 comprises according to a

Embodiment, as also shown in Fig. 1, one or more conveyor belts 50, 51. According to one embodiment of the invention by means of the transport device 5 acting at least in the levitation pad 3 tensile stress is exerted on the thin glass ribbon 1, wherein the tensile stress in the longitudinal direction 100th the thin glass band is located. During the transport process, the glass ribbon 1 is thus held under tension. This is favorable, among other things, to undefined transport conditions, such as local deformations or changes in altitude

Avoid levitation transport. This is done by the individual transport units before and after the

Laser cutting a preferably from unit to

Unit applied increasing tension on the tape. The transport units of the transport device 5 preferably comprise one or more conveyor belts. In the example of FIG. 1, two conveyor belts, wherein the conveyor belt 50 in the transport direction and the conveyor belt 51 in the transport direction behind the levitation pad. 3

are arranged. It is particularly favorable if a

Transport belt, which in the transport direction in front of the

Levitationsunterlage 3 is arranged (in the example of FIG. 1, the conveyor belt 50), a vacuum suction 53, to the thin glass ribbon on the conveyor belt

festzusaugen. This allows the exercise of sufficiently high tensile forces, without these possibly on upstream process steps, such as a

Pulling process from a melt or a preform, or even unwinding of the thin glass ribbon from a roll impact. Generally, without limitation to the specific

Embodiment of Fig. 1, it is for the

Stress risers according to the invention are favorable if the tensile stress exerted in the region of the levitation pad 3 on the thin glass ribbon 1 is at most 10 MPa in the longitudinal direction. Furthermore, a tensile stress of

at least 0.5 MPa preferred in order to fix the thin glass ribbon 1 well in its intended vertical position can. Particularly preferred is a tensile stress along the longitudinal direction 100 in the range of 0.8 MPa to 3.5 MPa. According to one embodiment is in the field of

Levitationsunterlage 3, here especially in the impingement of the cooling fluid a tensile stress of 2 MPa exercised.

As an alternative to the embodiment shown in FIG. 1, the levitation pad may also have a planar surface 30 or a surface 30 with a curvature axis 31 with a component along the longitudinal direction 100 of the thin glass ribbon 1, preferably parallel to the longitudinal direction 100. In particular, a convexly curved surface as shown in FIG. 2 is preferred. Such

Levitationsunterlage 3, which has a curvature axis along the longitudinal direction 100 of the thin glass ribbon 1, shows the perspective view of Fig. 2. The

Levitationsunterlage 30 with flat or curved parallel to the longitudinal axis convex curved surface leads to a curvature of the thin glass ribbon 1, the axis of curvature also extends in the longitudinal direction 100 of the thin glass ribbon. In the case of a flat surface, the bulge of the thin glass results through the course of the pressure field. At the opposite edges with the borders to be separated from the pressure from escaping gas is lower, so that the distance to the levitation pad 3 is lower here. Fig. 3 shows this schematically in

Longitudinal direction 100 of the thin glass ribbon 1 considers the

Levitation pad 3 with the stored on it

Thin Glass Band 1. The thickened ribbons 10, 11 are closer to the surface 30, while the center area of the

Thin glass bands 1 bulges. In both embodiments of FIGS. 2 and 3, therefore, a curvature of the

Thin glass bands 1 whose axis of curvature lies in the longitudinal direction 100 of the thin glass band 1. This leads to a mechanical voltage difference between the upper side 101 and lower side 102 of the thin glass band 1. In particular, arises at the

Top 101 of the thin glass ribbon 1, a tensile stress G _que r with direction transverse, in particular perpendicular to the longitudinal direction 100 of the band. In the sense of the invention, the upper side 101 is the side of the thin glass band 1 facing away from the levitation support 3 and the lower side 102 of the levitation support 3. The direction of the tension G _qU he is in Figs. 2 and Fig. 3 to

Explanation drawn. It is particularly advantageous, such a tensile stress in the region of the levitation pad 3, ie where the borders 10, 11 by

Tension trunks are separated, exercise to the Crack propagation support, even if the curvature and thus the resulting tensile stress are small. The tensile stress transverse to the longitudinal direction causes a crack-expanding force acts on the crack end.

In contrast, the voltage differences in

Longitudinal direction, unlike the arrangement known from US 2013/0126576 AI, only small. Although, as explained above, the application of a longitudinal tensile force is preferred, but this acts equally

Top 101 and bottom 102 of the thin glass ribbon. 1

In particular, therefore, according to a preferred

Embodiment of the invention provided that the

Thin glass band 1 is guided so that in the area of

Levitation pad 3 is a difference of less than 0.25 MPa between mechanical, acting in the longitudinal direction 100 of the tape stresses on top 101 and bottom 102 is present. Preferably, furthermore, that with a in

Longitudinally applied tensile force on the thin glass band in the area of the levitation pad 3, the ratio Δσ / σ is less than 0.5. Δσ is the difference between the longitudinal tensile stresses on the upper side 101 and lower side 102 and σ the tensile stress generated by the applied tensile force in the longitudinal direction. Preferably, the ratio Δσ / σ is less than 0.125.

By the with the leadership of the invention

Thin glass bands 1 over the levitation pad 3 caused

Tensile stress on one of the sides of the thin glass strip 1 is particularly suitable for separating the borders Glasses with a low coefficient of thermal expansion. The thermally induced here with laser and cooling fluid tensile stresses are corresponding to the smaller

Expansion coefficient lower. In particular, this relates to glasses with linear coefficients of thermal expansion CC <4 * 10 ^{~ 6} Kr ¹ . Such glasses are, for example, alkali-free borosilicate glasses which have a linear

Temperature expansion coefficient of less than 3.5 * 10 ^{~ 6} K ¹ have. Preferably, here in the field of

Levitation pad 3, in particular at the point of incidence 70 of the laser beam 7 by curvature of the thin glass ribbon 1 a tensile stress perpendicular to the longitudinal direction 100 exerted, so that the ratio σ / of tensile stress σ to linear

Thermal expansion coefficient CC is at least 0.07 * 10 ^{~ 6} MPa * K ^_1 .

With the heating by means of the laser and

subsequent cooling caused by the cooling jet temperature difference is the mechanical stress σ = -CTE ■ E ■ AT

(l) ²

In this equation, the factor CTE denotes the linear coefficient of thermal expansion, E the modulus of elasticity of the glass and ΔΤ the temperature difference produced. This stress then leads to crack propagation if it is greater than the minimum breaking stress

In this regard, the parameter Kic denotes the

Fracture toughness and the parameter a the critical crack length. The critical crack length corresponds to half the crack width The fracture toughness Ki _c is also considered more critical

Stress intensity sfaktor denotes. Especially

advantageous cutting properties arise for a voltage

σ> -σ _π

(3)

According to one embodiment of the invention, therefore, a temperature difference is generated by means of the laser and the cooling beam, which, with the combination of equations (1) to (3), at least the value

having .

The device 2 can via a control device

dispose of the control processes of the

inventive method controls. The control device can, for example, the pressure of the scoring device

and / or control the removal or lifting of the scoring device. Further examples are a power control of the laser, a flow control of the cooling jet generator 14, a pressure control for the Levitationsunterlage 3, a

Adjustment of a tensile force acting on the thin glass ribbon 1 in the longitudinal direction.

As a laser 72 for generating a laser beam 7 is

For example, a C02 ^~ laser suitable. In the in Fig. 1 In this case, two lasers 72 are provided in order to heat the dividing lines for the separation of the borders 10, 11 at both edges of the thin glass ribbon 1. Preferred laser powers are without limitation to a specific laser type in the range up to 200W.

The initially damaged surface area of the

Thin glass bands 1 is by the feed by means of

Transport device 5 in the focus 71 of the laser, such as a C02 ^~ laser brought and there heated by the registered laser energy to a temperature T <T _g and then rapidly cooled by spraying an aerosol by means of an aerosol generator 141. The aerosol generator 141 and thus the exiting aerosol jet 161 are, according to one embodiment, at an angle in the range of -20 ° to + 20 ° with respect to the surface normal of the

Thin glass bands, or accordingly also the

Normal of the surface of the levitation pad 3 inclined. According to one embodiment, the aerosol generator 141 is at an angle of 7 ° to the glass ribbon normal

inclined. In particular, an inclination is preferred in which the aerosol jet 161 a

Velocity component antiparallel to

Transport direction has.

By using a cooling fluid, the

Contains liquid droplets, the heated by the laser beam 7 glass can be cooled very quickly again. In this case, it is favorable if the distance between laser spot and cooling jet generator 14, or more precisely the distance of the point of incidence 70 of the laser beam 7 to the point of impact of the cooling jet 16, is chosen such that the entire Volume in the thickness direction of the glass ribbon by means

Heat conduction was warmed through.

After the laser-assisted voltage riser according to the invention, the braids 10, 11 according to an embodiment of the invention initially move next to the

Thin glass band 1 continue and are then from

Crushing rollers finally separated from the thin glass band 1 and fed to a shard bunker. The crushing rollers can be designed raised at two opposite positions, in order to ensure by mechanical stress exaggeration, the continuous opening of the crack.

When working with long thin glass bands, it is generally the case, irrespective of the manner of the severing method, that the guidance of the band can be problematic since the band has only a low degree of rigidity. This can lead to the lateral running of the band, as well as to wavy bending of the band.

These effects can interfere with the cutting process and lead to inaccuracies in the dimensions of the tape.

Regardless of whether a cooling fluid is provided or which constituents or phases comprise the cooling fluid, those shown in FIGS. 7 to 9 can be used by way of example

illustrated embodiments may be provided with which the aforementioned problems can be solved.

Fig. 7 shows an example of a device 2 for

Separating a thin glass ribbon 1 along its

Lengthwise 100, in this case for separating

Edge regions, in particular of borders 10, 11 of a Thin glass bands 1. The method that can be carried out with the apparatus 2 for separating a thin glass band 1 along its longitudinal direction 100, in this case for separating edge regions, in particular braids 10, 11 of a

Thin glass bands 1 is generally based on, without limitation, the use of a cooling jet

Thin glass ribbon 1 is guided with a thickness of at most 400 pm along the longitudinal direction 100 by means of a transport device 5 via a Levitationsunterlage 3, wherein in the area of Levitationsunterlage 3 a laser beam 7 is directed to the thin glass ribbon 100, which

Thin glass ribbon 1 at the impact point 70 of the laser beam 7 heats up and on which the thin glass ribbon 1 in the longitudinal direction 100 is moved so that the laser beam 7 extends in the longitudinal direction 100 of the thin glass ribbon 1 track 71 and by the local heating in the longitudinal direction 100 along the track 71 of Laser beam 7 to a

Crack propagation of the thin glass ribbon severing stress crack 15 leads.

The transport device 5, which is designed as a roller conveyor in the example of FIG. 7, generally comprises a roller arrangement 180, according to a development of the

Invention as in the example shown immediately before and behind the Levitationsunterlage 3. A

Roller assembly 180 includes a conveyor roller 182 for

Advancing the thin glass ribbon 1 and an opposite and arranged in juxtaposition to the conveying roller 182

Counter roll 184 for pressing the thin glass ribbon 1 to the conveying roller 180. The thin glass ribbon 1 is in each case between the roller assembly 180, in other words between the conveying roller 182 and the counter roller 184th passed along its longitudinal direction 100, preferably without slippage.

The thin glass band is thus pushed with a roller assembly 180 at the inlet of the system in this and guided through the system. This allows for safe guidance of the glass ribbon and allows unwanted lateral

Minimize deflection and vibration. Optionally, just as in the embodiment of FIG. 1, a cooling fluid can be blown onto the track 71 heated by the laser beam 7 so that the area heated by the laser beam 7 is cooled again and an additional mechanical stress is generated, which causes it to propagate one the glass ribbon 1 in

Lengthwise 100 along the track 71 of the laser beam 7 severing stress crack 15 leads.

The feed roller 182 of a roller assembly 180 is

preferably with a drive, such as a motor,

connected, while a counter-roller 184 does not necessarily require a drive. The counter roll 184 provides primarily for the pressure of the thin glass ribbon 1 to ensure sufficient friction for the feed.

As shown in simplified form in FIG. 7, in particular two counter-rollers 184 can be provided, which in each case roll in the edge region of the thin-glass strip 1. By means of such marginal mating rollers 184, a scratching of the

Thin glass bands 1 in the area between the counter rollers 184, ie in Gutglasbereich avoided. Furthermore, optionally a drift control can be provided, in that a different strong pressure by the marginal counter rollers 184 is exercised. In this way, the thin glass ribbon 1 can be controlled if necessary controlled. The conveyor rollers 182 of the roller assemblies 180 in front of and behind the levitation pad 3 may have a coupled drive to provide synchronous feed

guarantee . On the other hand, by means of both sides of the

Levitationsunterlage 3 arranged roller assemblies 180 a acting in the levitation pad 3

Tensile stress in the longitudinal direction 100 are exerted on the thin glass ribbon 1. For this purpose, it may be provided to set the feed of the conveyor rollers differently.

Fig. 8 shows another example of a device 2 for cutting a thin glass ribbon 1 along its

Lengthwise 100, in this case for separating

Edge regions, in particular of borders 10, 11 of a

Thin glass ribbon 100 is directed, which heats the thin glass ribbon 1 at the point of impact 70 of the laser beam 7 and on which the thin glass ribbon 1 in the longitudinal direction 100th is moved past, so that the laser beam 7 a in

Traces 71 extending longitudinally 100 of the thin glass ribbon 1 and draws by the local heating in the longitudinal direction 100 along the track 71 of the laser beam 7 to a

Crack propagation of the thin glass ribbon severing stress crack 15 leads. Optionally, by means of a cooling jet generator 14, a cooling fluid to the from

Laser beam 7 heated track 71 are blown, so that the area heated by the laser beam 7 is cooled again and a mechanical stress is generated, which leads to the propagation of the glass ribbon 1 in the longitudinal direction 100 along the track 71 of the laser beam 7 severing stress crack 15.

The device 2 shown in FIG. 8 comprises a

Blower 190 in juxtaposition to the

Levitationsunterlage 3, wherein the blower 190 blows a gas stream on the top 101 of the thin glass ribbon 1. This can be on the thin glass ribbon 1

spreading transverse waves are attenuated, for example, the breaking off of the borders 10, 11, mechanical shocks or guide vibrations

can be attributed. This solution can be provided as an alternative or in addition to the embodiment according to FIG. 7 in order to improve the belt stability.

While the blower 190 is blowing a gas flow onto the top 101 of the thin glass ribbon 1, a gas flow is blown onto the bottom 102 of the thin glass ribbon 1 by the levitation pad 3, so that a total of

double-sided gas cushion is formed. The

Blower 190 and the Levitationsunterlage 3 thus form a pneumatic damper for the

Thin glass band 1.

The fan 190 is powered by a pressure source, e.g. a pump 33, a compressed fluid, preferably supplied to air. Like the levitation pad 3, the blower 190 may have a plurality of openings on a surface facing the thin glass ribbon 1

exhibit. The compressed fluid escapes through openings on its surface facing the thin glass band 1, so that a gas cushion forms between the thin glass band 1 and the surface of the blower 190, which acts as a damper for the thin glass band 1. With regard to the pump 33 or alternative sources of compressed air, what has been said about the levitation pad 3 applies. In particular, the

Levitationsunterlage 3 and the blower 190 may also be connected to the same pump or compressed air source. The volume flow of the blower 190 can thus the levitation pad 3, possibly after deduction of a

Glass weight corresponding proportion.

Referring to FIG. 9, an apparatus 2 for separating a thin glass ribbon 1 comprises roller assemblies 180 in front of and behind the levitation pad 3, as well as a

Blower 190 in juxtaposition to the

Levitation Pad 3. In the example shown in Fig. 9, after leaving the roller assembly 180, the thin glass ribbon 1 is placed behind the levitation pad 3, i. after this

Separation process, led to the decoupling in a loop 195 and then wound onto a roll 200.

Especially for the separation of thin glasses prove Furthermore, certain beam profiles as low to produce a temperature gradient between top 101 and bottom 102. Such a temperature gradient is

particularly advantageous to achieve a high directional stability in the crack propagation.

For this purpose, according to an embodiment of the invention is generally, without limitation to the use of a cooling jet, a method for separating thin glass, in particular a thin glass ribbon 1, having a thickness of less than 400 .mu.m, preferably less than 250 .mu.m, provided in which the thin glass along a a parting line forming track 71 along a feed direction, namely the longitudinal direction 100, is heated progressively with a laser beam 7, so that by the thus produced temperature difference of the heated glass to the surrounding glass, a mechanical stress is generated in the glass and a crack in the form of a stress crack 15 following the mechanical stress propagates along the dividing line and the thin glass

severed, the laser beam 7, e.g. by means of a beam shaping optics, is shaped so that its

Beam profile 73 has an elongated shape, and wherein the laser beam 7 so on the surface of the

Thin glass is directed that the longitudinal direction 74 of the beam profile 73 is in the feed direction, and wherein the elongated shape of the beam profile is asymmetrical, so that the intensity profile at the ends 75, 76 of the beam profile 73 differs, such that the increase of the intensity at the the thin glass first sweeping forward end 75 is steeper than the drop in intensity of the opposite rear end 76. 10 shows, by way of example, a beam profile 73 described above, together with the longitudinal direction 100 of the thin glass band 1. The elongate shape of the beam profile is asymmetrical, with the ends 75, 76 of the beam profile

Distinguish beam profile, wherein the front end 75, which sweeps over the first glass during the feed, is formed by a transversely to the feed direction 100 extending edge 77. Furthermore, the rear end 76 of the beam profile 73 has a steadily decreasing towards the end

Intensity. The beam profile thus also has a shape tapering towards the rear end 76. For example, the beam profile 73 can be elliptical or pointed towards the end 76. The use of such an asymmetric beam profile increases the process stability and thus also the strength and the defined course of the produced glass edges. The shape of the profile can be easily produced, for example, by masking or shadowing one end of the laser spot.

In addition, it is favorable to design the beam profile and thus the temperature profile in such a way that a guidance of the crack propagation is achieved so that the crack stably follows the feed direction and does not break off laterally. Again, this proves to be difficult especially for thin glasses, since the voltage gradient, which can be built up by the heating, anyway smaller than thick glasses. For this purpose, according to a further development of the invention, a method for separating thin glass, in particular a thin glass strip 1, having a thickness of less than 400 μm, preferably with a thickness in the range of 5 pm to

150 pm, at which the thin glass along a

Dividing line 203 forming track 71 is progressively heated, wherein the heating of the glass by the energy of at least one energy source within a

Einwirkfeldes 204 this energy source, preferably by the energy of at least one laser beam 7 within the laser spot of this laser beam 7, is carried out on the thin glass, the Einwirkfeld 204 along the dividing line 203 is moved over the thin glass, so that through the

Temperature gradient of the means of at least one

Heated glass to the surrounding glass, a mechanical stress is generated in the glass, through which a crack in the form of a stress crack 15 propagates along the dividing line 203 following the mechanical stress, and wherein two portions of the Einwirkfelds 204 laterally spaced from the dividing line 203, and Einwirkfeld 204 einrahmen a section 214 through which the

Dividing line 203 runs, such that in the portion of this spacing areas of the thin glass adjacent to the dividing line

203 are heated more strongly than areas on the parting line 203, and wherein the Einwirkfeld 204 is formed so that when moving the thin glass along the parting line 203, these portions in the direction of movement of the thin glass

converge and meet on the dividing line 203.

In particular, the method described above can also be prepared in such a way that the thin glass is progressively heated along a track 71 forming a parting line 203, wherein the heating of the glass takes place by means of two energy sources, in particular two laser beams, each in an impact area 211, 212 the Glass, wherein the Einwirkfeld 204 is at least formed by the first and the second impact area, and wherein the energy sources are directed to the glass, that the impact areas 211, 212 are offset in the direction perpendicular to the separation line 203 laterally to each other, wherein the two impact areas 211, 212 in one

Overlap area 213 overlap, so that the

Dividing line 203 passes through this overlap area 213 and by the temperature difference of the means of

Energy sources heated glass to the surrounding glass, in particular along the dividing line 203 in the

Overlap area incoming glass a mechanical

Stress is generated in the glass, through which a crack in the form of a stress crack 15 of the mechanical

Following voltage along the dividing line 203 propagates.

Fig. 11 (a) generally shows two impact areas 211, 212 which together form an impact field or zone 204. Due to the mutually oblique orientation of the two impact regions 211, 212, a cutout 214 is located between these two regions. The impact regions 211, 212 overlap in an overlap region 213. Accordingly, the highest energy density is also achieved in this region. The glass now passes through this

Overlap area 213, there is a very steep increase in temperature compared to the cold glass, which runs along the parting line 203 in the overlap region. Accordingly, it comes here to a high

Voltage gradients and the propagation of the crack. The two non-overlapping areas of the impact areas now ensure a stable guidance of the crack. In case of a deviation of the course of the dividing line decreases by the also existing heating of the glass in these

Areas of temperature and thus the voltage gradient.

A portion of the Einwirkfeldes 204 can by a

Masking device (not shown here) are masked, whereby the cutout 214 is formed. 11 (b) shows, as an example, an exposure field 204 in FIG. 1 with a v-shaped cutout 214 facing its front, in the transport direction, which separates two subregions 242, 244 of the exposure field 204 so that they are spaced transversely to the parting line 203 the mutually facing edges of the sections run towards each other and in the

Intersection of the dividing line 203 meet with the Einwirkfeld 204. Such an exposure field 204 may also be generated with a single energy source by:

For example, as I said a masking is made. For example, the energy source may be a laser beam, with a portion of the laser spot forming the impingement area being blanked to form the cutout 214.

Claims

Claims:

Process for separating a thin glass ribbon (1) with a thickness of at most 400 pm along a

Longitudinal direction (100) of the thin glass band (1),

preferably for separating edge regions,

in particular of braids (10, 11) of the thin glass band

(1), wherein the thin glass ribbon (1) by means of a

Transport device (5) along its longitudinal direction

(100) is guided over a Levitationsunterlage (3), wherein in the region of the Levitationsunterlage (3) a laser beam (7) is directed to the thin glass ribbon (100), which the thin glass ribbon (1) at the point of impact

(70) of the laser beam (7) heats up and on which the thin glass ribbon (1) in the longitudinal direction (100) is moved past, so that the laser beam (7) has a in

Lengthwise (100) of the thin glass ribbon (1) extending trace (71) draws, and wherein by means of a

Cooling jet generator (14) a cooling fluid is blown onto the track (71) heated by the laser beam (7), so that the area heated by the laser beam (7) is cooled again and a mechanical tension is generated, which is used to propagate the glass ribbon (1). in the longitudinal direction (100) along the track (71) of

Laser beam (7) passing through the stress crack (15), and wherein the cooling fluid contains vapor of a liquid at a saturation ratio of at least 0.5 or liquid droplets, wherein the liquid droplets on the surface of the

Thin glass bands (1) form a contact angle which is smaller than that of water on the same surface. Method according to the preceding claim, characterized in that the cooling jet generator (14) is designed as an aerosol generator (141) which, as cooling fluid, blows an aerosol onto the track heated by the laser beam (7).

A method according to claim 1, characterized in that the cooling jet generator (14) as a

Ink jet printhead (142) is formed, which as a cooling fluid liquid droplets on the from

Laser beam (7) sprayed track sprays.

Method according to one of the preceding claims, characterized in that by means of a

Scoring device (9) at the beginning of the thin glass ribbon (1) before the impingement of the laser beam (7)

Initial defect is inserted, which by the

Impact point (70) of the laser beam (7) runs to initiate the stress crack.

Method according to the preceding claim, characterized in that after initiating the

Stress crack during crack propagation, the scoring device (9) from the surface of the

Thin glass bands (1) and thus the damage is terminated.

Method according to one of the two preceding claims, characterized in that the scoring device (9) comprises a scoring wheel (91), wherein the pressing force of the scoring wheel (91) upon introduction of the initial defect less than 4 N, preferably less than 1.5 N is.

Method according to one of the preceding claims, characterized in that braids (10, 11) of a thin glass ribbon (1) with a length of at least 10 meters, in particular in the range of 10 to 1000 meters in the longitudinal direction (100) of the thin glass ribbon (1)

be separated.

Method according to one of the preceding claims, characterized in that a fluid is supplied to the levitation pad (3) which has a pressure in the range of 0.1 to 4 bar, preferably in the range of 0.1 to 2 bar, particularly preferably in the range of 0.2 to 1.0 bar.

Method according to one of the preceding claims, characterized in that by means of

Transport device (5) has a tensile stress in at least in the region of the levitation support (3)

Longitudinal direction (100) on the thin glass ribbon (1) is applied.

Method according to one of the two preceding claims, characterized in that in the region of

Levitationsunterlage (3) on the thin glass ribbon (1) a tensile stress in the longitudinal direction in the range of 0.5 MPa to 10 MPa, preferably in the range of 0.8 MPa to 3.5 MPa is applied.

Method according to one of the preceding claims, characterized in that the thin-glass band (1) is advanced between a roller assembly (180) along its longitudinal direction (100).

Method according to one of the preceding claims, characterized in that the thin-glass band (1) is arranged between roller arrangements (180) on both sides of the

Levitationsunterlage (3) along its longitudinal direction (100) is advanced, in particular such that in the region of the levitation pad (3) acting tensile stress in the longitudinal direction (100) on the thin glass ribbon (1) is applied.

Method according to one of the preceding claims, characterized in that the upper side (101) of the thin glass band in the region of the levitation support (3) is blown with a gas stream, in particular in order to spread over the thin glass band (1)

to damp transversal waves.

Method according to one of the preceding claims, characterized in that a cooling fluid is sprayed on, the liquid droplets thereof

- Provided with surfactant water and / or

- Contain a monohydric or polyhydric alcohol, preferably ethylene glycol.

Method according to one of the preceding claims, characterized in that the glass surface is sprayed with a cooling fluid whose

Liquid droplets on the glass surface have a contact angle of less than 40 °, more preferably less than 20 °. Method according to one of the preceding claims, characterized in that the thin glass band (1) is guided such that in the region of the levitation pad

(3) a difference of less than 0.25 MPa between mechanical, longitudinal (100) thin glass ribbon

(1) acting stresses on top (101) and

Bottom (102) is present. 17. The method according to the preceding claim, characterized

characterized in that on the thin glass ribbon (1) a tensile force in the longitudinal direction (100) is applied, wherein in the region of the levitation pad (3) the ratio Δσ / σ is less than 0.5, preferably less than 0.125, where Δσ is the difference of in Longitudinal tensile stresses on top (101) and

Bottom (102) and σ by the applied

Traction force in the longitudinal direction (100) designate generated tensile stress.

18. Method according to one of the preceding claims,

characterized in that by curvature of the

Thin glass bands (1) at the point of impact (70) of the

Laser beam (7) has a tensile stress perpendicular to

The longitudinal direction of the thin glass ribbon (100) is applied, so that the ratio σ / of tensile stress σ to linear thermal expansion coefficient CC

is at least 0.07 * 10 ^{~ 6} MPa * ^ ¹ .

Method according to one of the preceding claims, characterized in that the temperature difference ΔΤ caused by the heating by means of the laser beam (7) and the cooling is achieved by means of the cooling fluid, at least the value ΔΓ = (7 · K _lc ) / (5 · ' ^{2 ■} CTE-E) assumes, the parameter Ki _c the fracture toughness, the parameter a the critical crack length , the factor CTE denotes the linear coefficient of thermal expansion and E the elastic modulus of the glass.

20. Method according to one of the preceding claims,

characterized in that the laser beam (7) is shaped so that its beam profile (73) has an elongated shape, and wherein the

Laser beam (7) is directed onto the surface of the thin glass so that the longitudinal direction (74) of the

Beam profile (73) is in the feed direction, and wherein the elongated shape of the beam profile is asymmetrical, so that the intensity profile at the ends (75, 76) of the beam profile (73)

such that the increase in intensity at the forward first (75) first sweeping the thin glass is steeper than the decrease in the intensity of the opposite rear end (76).

21. A device (2) for separating a thin glass ribbon (1) having a thickness of at most 400 μm along a longitudinal direction (100) of the thin glass ribbon (1),

in particular for separating edge regions,

in particular of braids (10, 11) of the thin glass band (1), designed for carrying out a method according to one of the preceding claims, which comprises a levitation substrate (3) and a transport device

(5) for guiding the thin-glass band (1) along its longitudinal direction (100) over the leveling pad (3). The apparatus (2) comprises a laser (72) for directing a laser beam (7) onto the thin glass band (100) in the region of the levitation support (3) and the thin glass band (1) at the point of impact (70) of the laser beam (7) to heat up, so that the

Laser beam (7) in a longitudinal direction (100) of the

Thin glass bands (1) running track (71) records when the thin glass ribbon (1) by means of the transport device

(5) on the laser beam (7) in the longitudinal direction (100)

wherein the device (2) further comprises a cooling jet generator (14) for blowing a cooling fluid onto the track (71) heated by the laser beam (7) so that the area heated by the laser beam (7) is cooled again and a mechanical tension is generated, which for

Reproduction of the glass ribbon (1) in the longitudinal direction

(100) leads along the track (71) of the laser beam (7) severing stress crack (15), and wherein the device (2) further at least one

Liquid reservoir includes, which includes a liquid for generating a cooling fluid

is provided, the vapor of the liquid at a saturation ratio of at least 0.5 contains or contains liquid droplets, wherein the

Liquid droplets on the surface of the

Thin glass bands (1) form a contact angle which is smaller than that of water on the same surface. 22. Device according to the preceding claim, characterized in that the cooling jet generator (14) is designed as an aerosol generator (141), as Cooling fluid blows an aerosol on the track heated by the laser beam (7).

Apparatus according to claim 21, characterized in that the cooling jet generator (14) as a

Laser beam (7) blowing heated track.

Device according to one of the preceding claims, characterized in that the levitation pad (3) has a flat surface (30) or a surface (30) with a curvature axis with a component along the longitudinal direction (100) of the thin glass ribbon (1).

Device according to one of the preceding claims, characterized in that the transport device

(5) comprises a roller assembly (180), wherein the roller assembly (180) at least one conveying roller (182) for advancing the thin glass band (1) and at least one opposite and in opposition to

Feed roller (182) arranged counter roller (184) for pressing the thin glass ribbon (1) to the feed roller

(180) for advancing the thin glass ribbon (1) between the conveying roller (182) and the counter roller (184) along its longitudinal direction (100).

Device according to one of the preceding claims, characterized in that the transport device (5) roller assemblies (180) on both sides of

Levitation document (3) includes, in particular, to a tensile stress in the longitudinal direction (100) acting in the region of the levitation support (3) on the

Thin glass band (1) exercise.

Device according to one of the preceding claims, comprising a fan device (190) in FIG

Juxtaposed to the levitation pad (3), wherein the blower means (190) blows a gas stream onto the top surface (101) of the thin glass ribbon (1),

in particular, in order to attenuate transversal waves propagating over the thin glass ribbon (1).